1. Field of the Invention
The present invention relates to a helical-blade fluid machine applicable to compressors, expansion machines, pumps, etc.
2. Description of the Prior Art
A helical-blade fluid machine has, in a closed casing, a cylinder and a roller piston eccentrically arranged in the cylinder. The peripheral surface of the roller piston has a helical groove in which a helical blade is inserted to define compression chambers in the cylinder. Relative motion between the cylinder and the roller piston draws coolant gas from an intake end of the cylinder into the compression chambers and successively conveys and compresses the gas toward a discharge end of the cylinder. The compressed gas fills the casing and is discharged outside.
Generally, the helical-blade fluid machine directly draws gas into a compression mechanism, compresses the gas therein, once discharges the compressed gas into the casing, and sends the gas outside through a discharge pipe attached to the casing. As a result, the casing must contain a high-pressure atmosphere. The compression mechanism intrinsically has a long axis that needs long bearings.
The compression mechanism is conventionally designed to partly submerge in a lubricant pool in the casing. This dissolves much coolant in the lubricant under the high-pressure atmosphere, thereby increasing the temperature of the lubricant and decreasing the viscosity thereof to improperly lubricate the long bearings of the compression mechanism.
The coolant may be an HFC-based high-pressure coolant, which has a very high saturation pressure. For example, the saturation pressure of R410A is about 1.5 times higher than that of conventional R22. The casing of the fluid machine must withstand such high pressure. Namely, the casing must have a thick wall, which increases the weight as well as cost of the fluid machine.
When the roller of the compression mechanism in the lubricant pool is driven, it stirs the lubricant, to destabilize the supply of the lubricant, thereby destabilizing the torque and total operation of the compression mechanism.
An object of the present invention is to provide a helical-blade fluid machine capable of isolating lubricant from high pressure and high temperature and properly lubricating sliding parts of a compression mechanism.
Another object of the present invention is to provide a helical-blade fluid machine having a casing that is thin and light.
Still another object of the present invention is to provide a helical-blade fluid machine having a roller that does not stir lubricant, thereby securing the stable operation of a compression mechanism.
Still another object of the present invention is to provide a helical-blade fluid machine capable of separating coolant gas from coolant liquid, preventing a compression mechanism from drawing the coolant liquid, to prevent an overload operation, avoiding the coolant gas from being heated, and securing efficient compressing conditions.
In order to accomplish the objects, an aspect of the present invention provides a helical-blade fluid machine having a closed casing, a cylinder arranged in the casing, a roller eccentrically arranged in the cylinder, a helical blade having unequal pitches to define compression chambers between the cylinder and the roller so that the volumes of the compression chambers gradually decrease in an axial direction, a drive mechanism for swaying the roller with respect to the cylinder, to axially move each of the compression chambers so that the volume of the compression chamber gradually decreases to compress gas contained therein, an intake pipe connected to the casing to guide gas into the casing and fill the casing with a low-pressure atmosphere, and a discharge pipe communicating with a discharge-end one of the compression chambers, to guide compressed gas from the discharge-end compression chamber to the outside of the casing.
The cylinder, roller, and helical blade form a compression mechanism, which is driven by the drive mechanism. The drive mechanism is electrical and is disposed under the compression mechanism.
The compression mechanism may draw gas from a lower part thereof and compresses the gas in the compression chambers while conveying the gas upwardly.
The compression mechanism may draw gas from the peripheral face of the cylinder into the compression chambers.
The compression mechanism may draw gas from a lower part of the roller into the compression chambers.
This fluid machine isolates gas drawn into the machine from lubricant and efficiently feed the gas into the compression chambers. The lubricant is under a low-pressure atmosphere containing the gas drawn into the casing, and therefore, is free from high pressure or high temperature. As a result, the lubricant maintains proper viscosity to smoothly lubricate bearings that are axially long. The low-pressure atmosphere in the casing enables the casing to have a thin wall to reduce the weight thereof. The roller never agitates the lubricant, thereby stabilizing the operation of the compression mechanism.
The present invention prevents lubricant that has lubricated the bearings from dropping onto a rotor of the drive mechanism and being scattered thereby. To realize this, a lubricant passage is formed through a first support frame that supports a rotating shaft of the compression mechanism. The lubricant that has lubricated the bearings of the compression mechanism passes through the lubricant passage and drops on or around a stator of the drive mechanism.
The fluid machine may have a first volume chamber in the cylinder and a second volume chamber above the cylinder. The first and second volume chambers communicate with each other, isolate discharged gas from lubricant, muffle noise, and reduce passage resistance.
The cross-sectional area of the first volume chamber may be tapered to widen toward the second volume chamber.
A check valve may be arranged in a port between the first and second volume chambers, to prevent a reverse flow from the second volume chamber toward the first volume chamber.
To secure a sealed state for a long time between a high-pressure area and a low-pressure area, an annular seal may be arranged around the second volume chamber or around an end face of the roller. The center of the annular seal is aligned with the center of the shaft.
It is preferable in this case that the bottom of the second volume chamber serves as a bearing to support the top end of the shaft.
In the fluid machine, a second support frame has a bearing for supporting the top of the shaft. To surely lubricate a top part of the compression mechanism, a lubricant passage axially formed through the shaft and a bearing space formed between the top end of the shaft and the bearing of the second support frame are used to lubricate the bearing of the second support frame.
The lubricant passage axially formed through the shaft is shifted from the axis of the shaft so that lubricant may smoothly rise in the passage due to centrifugal force.
To properly lubricate sliding parts of the compression mechanism, the lubricant passage formed through the shaft is connected to a lower part of the bearing of the first support frame and an upper part of the bearing of the roller.
To prevent the vibratory rotation of the drive mechanism, the shaft is shared by the drive mechanism and compression mechanism, and an end of the shaft passed through the drive mechanism is supported by a third support frame.
To balance the compression mechanism with centrifugal force, first and second balancers are attached to the shaft in the roller of the compression mechanism.
To prevent gas from being heated or from catching lubricant, the compression mechanism may be constituted to draw gas from an upper part thereof and compress the gas while conveying it downwardly.
To surely seal a high-pressure part from a low-pressure part in a compressed gas discharging area, a seal may be arranged on the discharge side of the roller of the compression mechanism.
To provide a muffling effect, a volume chamber communicating with a discharge-end one of the compression chambers may be formed at the periphery of the cylinder of the compression mechanism.
To minimize the lengths of power-supply wires, a terminal fitting for supplying power to the drive mechanism may be attached to the casing in a space that is formed on the casing and faces the cylinder of the compression mechanism.
The terminal fitting may be arranged at a cut of the first support frame that supports the shaft of the compression mechanism.
To always lubricate an Oldham ring for swaying the roller of the compression mechanism without rotating the same, the Oldham ring may be arranged between the bottom face of the roller and a lubricant passage area, which is formed on the first support frame to drop lubricant on or around the stator of the drive mechanism.
Another aspect of the present invention provides a helical-blade fluid machine having a compression mechanism composed of a cylinder, a roller, and a helical blade, a drive mechanism for driving the compression mechanism, and a casing for accommodating the compression and drive mechanisms in such a way as to simplify the structure of the machine and prevent the vibratory rotation of the drive mechanism. The fluid machine draws gas into the casing, compresses the gas in the compression mechanism, and discharges the compressed gas outside the casing. The compression mechanism is positioned above the drive mechanism. The compression mechanism and drive mechanism share a shaft that is rotatively supported by two support frames arranged on opposite sides of the drive mechanism.
Still another aspect of the present invention provides a helical-blade fluid machine having a compression mechanism composed of a cylinder, a roller, and a helical blade, a drive mechanism for driving the compression mechanism, and a casing accommodating the compression and drive mechanisms. The fluid machine draws gas into the casing through an intake pipe to fill the casing with a low-pressure atmosphere. The compression mechanism is arranged at a lower part of the casing, and the drive mechanism at an upper part thereof.
This fluid machine draws gas into the casing through the intake pipe to fill the casing with a low-pressure atmosphere so that the pressure and temperature of the atmosphere do not affect lubricant and so that the lubricant may secure proper viscosity. Since the compression mechanism is arranged at a lower part of the casing, the head of lubricant from the bottom of the casing is short to smoothly lubricate bearings and the compression mechanism. The casing may have a thin wall to reduce the weight thereof.
To prevent coolant liquid from being directly sent into compression chambers together with coolant gas, the intake pipe may be arranged in a space above the drive mechanism so that the coolant liquid may be gasified by heat.
A rotary plate may be attached to the top of a rotor of the drive mechanism, to spin off coolant liquid sent with coolant gas through the intake pipe.
The intake pipe may be arranged between the drive mechanism and the compression mechanism so that coolant gas may cool the drive mechanism and improve the efficiency of the fluid machine.
The compression mechanism may draw gas from an upper part thereof and discharge it from a lower part thereof, to improve a gas drawing efficiency.
An intake port of the compression mechanism may be formed on the peripheral wall of a balancer chamber which is formed inside the roller and in which a balancer attached to a shaft rotates, so that gas may be sent into the compression mechanism with centrifugal force.
The intake port may communicate with the casing through the balancer chamber and an intake passage formed in the shaft.
The intake passage formed in the shaft may have a separator for separating gas from lubricant.
The intake passage formed in the shaft may have a check valve to allow only a flow from the casing toward the intake passage.